Hi Colin,
It seems that there is a currency mismatch on the backend. I am giving you the steps below to contact an agent who can change it for you and update the currency and region. This is a user-to-user support forum.
Please contact Microsoft Support for further assistance.
Please go to the https://support.microsoft.com/contactus page
Type "Billing" and press Enter.
Please click on the "Contact support" button at the bottom.
Select the Product and Category for support based on your requirements.

I hope this information helps. If you have any more questions, don't hesitate to reach out.
Otherwise, if your problem is resolved, please mark this query as closed by pressing yes. Wishing you good luck!